Monday, September 14, 2009
2:44 PM

I had started my first job with a veterinarian in the late 1970s when the parvovirus outbreak occurred. Scores of dogs were admitted with bloody diarrhea, the smell of which could literally choke you. If memory serves, it took about nine months for the outbreak to run its course, and those were not happy days for veterinary technicians, I assure you. Almost all the dogs recovered, and life went on.

Of course, such a canine health crisis did not go unnoticed by the drug companies, who naturally came up with a vaccine for the disease. Its sudden appearance spurred research into its source, which seems to be feline panleukopenia, which somehow morphed into a canine virus. There is a theory that this mutation occurred in the laboratory, most likely while producing panleukopenia vaccines.

Symptoms of "parvo" are, besides the bloody diarrhea, vomiting, dehydration, fever, lethargy and anorexia (no appetite). The treatment is still supportive, consisting mostly of fluid administration until the disease runs its course. The vomitus and feces can carry the virus, so scrupulous clean-up is a must.

Canine parvovirus vaccines seem to vary widely in their efficacy. As I recall from my vet tech days, dogs were initially inoculated with the feline panleukopenia (distemper) vaccine, which was thought to be similar enough to induce immunity. Wrong! After experimenting with killed virus, a modified live version came out that instilled a limited immune response. By this time, however, the disease had mutated into two distinct strains, so the vaccine lost efficacy after a time.

Parvovirus vaccines don't work well on young pups. Otherwise, in adults, protection lasts approximately 5 years; due to the modified-live aspect of the vaccine, though, more side effects can occur. Intestinal as well heart problems have been reported in inoculated dogs, and side effects are exacerbated when given in tandem with other vaccines. Since parvoviruses depress the immune system, the list of health problems that could conceivably occur with repeated vaccination seems endless.

What to do? If you really need to inoculate your dog against this disease, it seems prudent to wait until he's older than 16 weeks, give the parvovirus shot separate from all others, and don't inoculate again until at least 5 years. This should give your dog protection without unduly taxing his immune system.